hi i just started learning LISP like 1 months ago. so i'm just really not that good with it. anyways, i'm suppose to do like program about disease and their symptoms using common lisp.basically the program will ask if the patient have this symptoms or not, the patient suppose to answer yes or no,then the system will just tell the patient of their disease. i did a few try but failed though. so this is my last resort. if none of you guys know.. im not gonna try anymore. haha.. maybe i should give up on LISP and take on VB instead. lol

You might want to buy the book Paradigms of Artificial Intelligence Programming. It's a great book both about AI as well as Common Lisp. All the examples in the book are done in CL, including a pretty sophisticated medical diagnosis program (based on some of the MYCIN work, if I remember right). If you want to do a simpler version of that, then the basic "what animal am I thinking of?" program might be what you're looking for. Try Paul Graham's On Lisp, which you can find online.

This is a very simple task. I'm not going to make everything for you, but, if you can make an algorithm (e.g. in pseudo-language) then it is very simple to transform it into Common Lisp. If you have the algorithm and cannot translate it into CL, you should try learning a bit of CL first.

Or you might choose a different data representation based on what you like. This is just to illustrate that if you put the data in the right format for your problem, the program will practically write itself.